| 1. |
- Eriksson, Henrik, et al.
(författare)
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Conjugacy of Coxeter elements
- 2009
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Ingår i: The Electronic Journal of Combinatorics. - 1097-1440 .- 1077-8926. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- For a Coxeter group (W, S), a permutation of the set S is called a Coxeter word and the group element represented by the product is called a Coxeter element. Moving the first letter to the end of the word is called a rotation and two Coxeter elements are rotation equivalent if their words can be transformed into each other through a sequence of rotations and legal commutations. We prove that Coxeter elements are conjugate if and only if they are rotation equivalent. This was known for some special cases but not for Coxeter groups in general.
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| 2. |
- Andrighetto, Giulia, et al.
(författare)
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Changes in social norms during the early stages of the COVID-19 pandemic across 43 countries
- 2024
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Ingår i: Nature Communications. - : NATURE PORTFOLIO. - 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of COVID-19 dramatically changed social behavior across societies and contexts. Here we study whether social norms also changed. Specifically, we study this question for cultural tightness (the degree to which societies generally have strong norms), specific social norms (e.g. stealing, hand washing), and norms about enforcement, using survey data from 30,431 respondents in 43 countries recorded before and in the early stages following the emergence of COVID-19. Using variation in disease intensity, we shed light on the mechanisms predicting changes in social norm measures. We find evidence that, after the emergence of the COVID-19 pandemic, hand washing norms increased while tightness and punishing frequency slightly decreased but observe no evidence for a robust change in most other norms. Thus, at least in the short term, our findings suggest that cultures are largely stable to pandemic threats except in those norms, hand washing in this case, that are perceived to be directly relevant to dealing with the collective threat. Tightness-looseness theory predicts that social norms strengthen following threat. Here the authors test this and find that, after the emergence of the COVID-19 pandemic, hand washing norms increased, but no evidence was observed for a robust change in most other norms.
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| 3. |
- Bernard, Mark, et al.
(författare)
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The subgroup problem : When can binding voting on extractions from a common pool resource overcome the tragedy of the commons?
- 2013
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Ingår i: Journal of Economic Behavior and Organization. - : Elsevier BV. - 0167-2681 .- 1879-1751. ; 91, s. 122-130
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Tidskriftsartikel (refereegranskat)abstract
- Using a common pool resource game protocol with voting we examine experimentally how cooperation varies with the level at which (binding) votes are aggregated. Our results are broadly in line with theoretical predictions. When players can vote on the behavior of the whole group or when leaders from each group can vote for the group as a whole, extraction levels from the common resource pool are close to the social optimum. When players extract resources individually, there is substantial overextraction. When players vote in subgroups, there is initially less overextraction but it increases over time. This suggests that in order for binding voting to overcome the tragedy of the commons in social dilemmas, it should ideally affect the group as a whole.
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| 4. |
- Cownden, Daniel, et al.
(författare)
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A popular misapplication of evolutionary modeling to the study of human cooperation
- 2017
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Ingår i: Evolution and human behavior. - : Elsevier BV. - 1090-5138 .- 1879-0607. ; 38:3, s. 421-427
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Tidskriftsartikel (refereegranskat)abstract
- To examine the evolutionary basis of a behavior, an established approach (known as the phenotypic gambit) is to assume that the behavior is controlled by a single allele, the fitness effects of which are derived from a consideration of how the behavior interacts, via life-history, with other ecological factors. Here we contrast successful applications of this approach with several examples of an influential and superficially similar line of research on the evolutionary basis of human cooperation. A key difference is identified: in the latter line of research the focal behavior, cooperation, is abstractly defined in terms of immediate fitness costs and benefits. Selection is then assumed to act on strategies in an iterated social context for which fitness effects can be derived by aggregation of the abstractly defined immediate fitness effects over a lifetime. This approach creates a closed theoretical loop, rendering models incapable of making predictions or providing insight into the origin of human cooperation. We conclude with a discussion of how evolutionary approaches might be appropriately used in the study of human social behavior.
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| 5. |
- Cownden, Daniel, et al.
(författare)
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The implications of learning across perceptually and strategically distinct situations
- 2018
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Ingår i: Synthese. - : Springer Science and Business Media LLC. - 0039-7857 .- 1573-0964. ; 195:2, s. 511-528
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Tidskriftsartikel (refereegranskat)abstract
- Game theory is a formal approach to behavior that focuses on the strategic aspect of situations. The game theoretic approach originates in economics but has been embraced by scholars across disciplines, including many philosophers and biologists. This approach has an important weakness: the strategic aspect of a situation, which is its defining quality in game theory, is often not its most salient quality in human (or animal) cognition. Evidence from a wide range of experiments highlights this shortcoming. Previous theoretical and empirical work has sought to address this weakness by considering learning across an ensemble of multiple games simultaneously. Here we extend this framework, incorporating artificial neural networks, to allow for an investigation of the interaction between the perceptual and functional similarity of the games composing the larger ensemble. Using this framework, we conduct a theoretical investigation of a population that encounters both stag hunts and prisoner’s dilemmas, two situations that are strategically different but which may or may not be perceptually similar.
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| 6. |
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| 7. |
- Enquist, Magnus, 1955-, et al.
(författare)
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Modelling the evolution and diversity of cumulative culture
- 2011
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 366:1563, s. 412-423
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Tidskriftsartikel (refereegranskat)abstract
- Previous work on mathematical models of cultural evolution has mainly focused on the diffusion of simple cultural elements. However, a characteristic feature of human cultural evolution is the seemingly limitless appearance of new and increasingly complex cultural elements. Here, we develop a general modelling framework to study such cumulative processes, in which we assume that the appearance and disappearance of cultural elements are stochastic events that depend on the current state of culture. Five scenarios are explored: evolution of independent cultural elements, stepwise modification of elements, differentiation or combination of elements and systems of cultural elements. As one application of our framework, we study the evolution of cultural diversity (in time as well as between groups).
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| 8. |
- Enquist, Magnus, et al.
(författare)
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One cultural parent makes no culture
- 2010
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Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 79:6, s. 1353-1362
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Tidskriftsartikel (refereegranskat)abstract
- The ability to acquire knowledge and skills from others is widespread in animals and is commonly thought to be responsible for the behavioural traditions observed in many species. However, in spite of the extensive literature on theoretical analyses and empirical studies of social learning, little attention has been given to whether individuals acquire knowledge from a single individual or multiple models. Researchers commonly refer to instances of sons learning from fathers, or daughters from mothers, while theoreticians have constructed models of uniparental transmission, with little consideration of whether such restricted modes of transmission are actually feasible. We used mathematical models to demonstrate that the conditions under which learning from a single cultural parent can lead to stable culture are surprisingly restricted ( the same reasoning applies to a single social-learning event). Conversely, we demonstrate how learning from more than one cultural parent can establish culture, and find that cultural traits will reach a nonzero equilibrium in the population provided the product of the fidelity of social learning and the number of cultural parents exceeds 1. We discuss the implications of the analysis for interpreting various findings in the animal social-learning literature, as well as the unique features of human culture.
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| 9. |
- Eriksson, Kimmo, et al.
(författare)
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A Below-Average Effect with Respect to American Political Stereotypes on Warmth and Competence
- 2015
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Ingår i: Political Psychology. - : Wiley. - 0162-895X .- 1467-9221. ; 36:3, s. 341-350
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Tidskriftsartikel (refereegranskat)abstract
- The "above-average effect" is the phenomenon that people tend to judge themselves above average on desirable traits. Based on social identity theory, we propose that a "below-average effect" may arise when individuals rate themselves and the average ingroup member on traits stereotypically associated with the ingroup. In two studies, Republican and Democrat participants rated themselves and the average political ingroup member on possession of desirable traits related to warmth and competence. Current political stereotypes in America associate the former dimension with Democrats and the latter with Republicans. Consistent with our hypothesis, the above-average effect was moderated by political group and dimension in interaction. In particular, Democrats rated themselves below the average Democrat on warmth and Republicans rated themselves below the average Republican on competence.
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| 10. |
- Eriksson, Kimmo, 1967-, et al.
(författare)
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A formal model accounting for measurement reliability shows attenuated effect of higher education on intelligence in longitudinal data
- 2024
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Ingår i: Royal Society Open Science. - : Royal Society Publishing. - 2054-5703. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- The effect of higher education on intelligence has been examined using longitudinal data. Typically, these studies reveal a positive effect, approximately 1 IQ point per year of higher education, particularly when pre-education intelligence is considered as a covariate in the analyses. However, such covariate adjustment is known to yield positively biased results if the covariate has measurement errors and is correlated with the predictor. Simultaneously, a negative bias may emerge if the intelligence measure after higher education has non-classical measurement errors as in data from the 1970 British Cohort Study that were used in a previous study of the effect of higher education. In response, we have devised an estimation method that used iterated simulations to account for both classical measurement errors in the covariate and non-classical errors in the dependent variable. Upon applying this method in a reanalysis of the data from the 1970 British Cohort Study, we find that the estimated effect of higher education diminishes to 0.4 IQ points per year. Additionally, our findings suggest that the impact of higher education is somewhat more pronounced in the initial 2 years of higher education, aligning with the notion of diminishing marginal cognitive benefits.
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